In the art of pipe fittings, there has been a continuing need to provide a suitable coupling for connecting two sections of similar pipe or connecting a section of one type of pipe to a section of another type of pipe of generally the same diameter. The criteria for such couplings includes the requirement of restraining the pipe sections from axial separation from each other when subjected to forces generated by hydrostatic pressure as well as external forces tending to deflect or separate one pipe section from another.
Prior art couplings that provide for restraining the pipe sections from axial separation are typically subject to very limited applications, are somewhat cumbersome to install, and/or provide relatively low restraining or holding capability against fluid pressure and other forces acting on the coupled pipe sections. Accordingly, the need for an improved coupling or so-called restrained sleeve has included the desiderata of providing a device which is operable to join the plain ends of pipes of either similar or dissimilar materials, is mechanically uncomplicated, is easy to install and has the capability to maintain joined pipe sections coupled in a fluid tight relationship under substantial fluid pressures within the pipe sections. It is to these ends that the present embodiment has been developed.